Seal

ABSTRACT

A sealing means for permitting continuous passage of a web material through a gap in a wall separating two zones at different pressures whilst minimising the flow of air from one zone to the other, comprising, built into the gap, two bearing members between which the web material passes, the first bearing member comprising a series of parallel, closely abutting, fingers which extend the full length of the gap, said fingers being pivoted on an axle which is parallel to a longitudinal edge of the gap, and each of the fingers being pressure loaded towards the second bearing member so as to maintain firm contact with either the web material or with the second bearing member, seals being provided between the fingers and the adjacent edges of the gap and also between the second bearing member and the adjacent edges of the gap, and the use of such sealing means in apparatus primarily intended for the continuous vacuum transfer printing of synthetic textile materials.

Jamin Feb. 25, 1975 [541 SEAL [75] Inventor: Guillaume Ward Jamin,

Manchester, England [73] Assignee: Imperial Chemical Industries Limited, London, England [22] Filed: Jan. 30, 1974 [211 App]. No.: 437,879

[30] Foreign Application Priority Data Primary Examinerl(enneth W. Sprague Assistant Examiner-James C. Yeung Attorney, Agent, or F irm-Cushman, Darby & Cushman [57] ABSTRACT A sealing means for permitting continuous passage of a web material through a gap in a wall separating two zones at different pressures whilst minimising the flow of air from one zone to the other, comprising, built into the gap, two bearing members between which the web material passes, the first bearing member comprising a series of parallel, closely abutting, fingers which extend the full length of the gap, said fingers being pivoted on an axle which is parallel to a longitudinal edge of the gap, and each of the fingers being pressure loaded towards the second bearing member so as to maintain firm contact with either the web material or with the second bearing member, seals being provided between the fingers and the adjacent edges of the gap and also between the second bearing member and the adjacent edges of the gap, and the use of such sealing means in apparatus primarily intended for the continuous vacuum transfer printing of synthetic textile materials.

4 Claims, 6 Drawing Figures FIG I PATENTEDFEB25|9Y5 3.867. 768

SHEET 30F 6 FIG m SEAL The chamber is preferably evacuated to a vacuum of at least inches (635 mms.) of mercury,'and, preferably to a vacuum in the region of 27 to 30 inches (685 to 760 mms.) of mercury. When the process is carried out in an intermittent manner a press is used in which the enclosed chamber comprises the space between two platens which is bounded by a sealing strip, the said space being connected to a suitable source of vacuum, and in this type of apparatus there is no difficulty in readily. achieving the required amount of vacuum. However, in order to carry out the process in a continuous manner it is necessary for the transfer paper and the textile material to be passed over a heated surface inside a vacuum chamber. Whilst the rolls of transfer paper and the textile material, both before and after the heat treatment, can be stored within the vacuum chamber, provision of such storage space markedly increases the size of the chamber thus resulting in increased loads onthe chamber due to atmospheric pressure. Further the process has to be interrupted in order to remove the rolls of treated textile material and used transfer paper and to insert new rolls of transfer paper and/or textile material. These difficulties could be overcome by passing the textile material and the transfer paper through a vacuum chamber containing therein the heated surface, the textile material and the transfer paper entering and leaving the chamber through seals which would minimise the entry of air into the evacuated chamber. Whilst the entry ofa small amount of air into the evacuated chamber can be dealt with by means of a suitable source of vacuum, thusenabling the required degree of vacuum to be maintained within the chamber, sealing systems currently available allow too much air to be admitted into the evacuated chamber so that in practice the required degree of vacuum cannot be maintained. The present invention is directed to improved sealing systems which whilst freely allowing the passage of the textile material and/or the transfer paper through the seal minimise the flow of air through the seal.

According to the invention there is provided a sealing means for permitting continuous passage of a web material through a gap in a wall separating two zones at different pressures whilst minimising the flow of air from one zone to the other, comprising, built into the gap, two bearing members between which the web material passes, the first bearing member comprising a series of parallel, closely abutting, fingers which extend the full length of the gap, said fingers being pivoted on an axle which is parallel to a longitudinal edge of the gap, and each of the fingers being pressure loaded towards the second bearing member so as to maintain firm contact with either the web material or with the second bearing member, seals being provided between the fingers and the adjacent edges of the gap and also between the second bearing member and the adjacent ler rotatable about a longitudinal axle which is preferably parallel to the lowest edge of the gap, a series of parallel, closely abutting, fingers which are pivoted on an axle which is parallel to the lowest edge of the gap, or a fixed bearing member the surface of which comes into contact with the web materialor with the series of fingers and which is covered with a layer of PTFE or a soft material such as rubber or a urethane, or which comprises an inflated tube ofa material such as rubber.

This second bearing member preferably forms the lower bearing member of the seal and is situated adjacent to the lowest edge of the gap so that the portion of the surface of this bearing member which comes into contact with the web material or the series of fingers is in a horizontal plane parallel to the said lowest edge. Seals are provided between this second bearing member and the adjacent edges of the gap. When this second bearing member is moveable in anyway, as for example a cylindrical roller which rotates, then the seal between such a bearing member and the lowest edge of the gap is a flexible seal which is attached to the lowest edge of the gap and is maintained in uniform contact with this bearing member by springs or other pressure means.

The fingers which form the first bearing member are pivoted on an axle which is parallel to the longitudinal edges of the gap and are so positioned that their lower edges can bear on the upper surface of the second bear ing member. Preferably the bearing area of the fingers is increased by having the relevant part of the lower edges of the fingers in the form of a curved section the radius of which corresponds to that of the upper surface of the second bearing member. The fingers are maintained in firm contact with the second bearing member by a pressure loading device attached to each finger. Seals are also provided between the end fingers in the row and the end walls of the gap and also between the leading and top edges of the fingers and the upper edge of the gap.

If the second bearing member comprises a series of fingers then these can be similar in construction and mounting to the series of fingers comprising the first bearing member, except that they are pressure loaded in the opposite direction so that they exert a pressure against the series of fingers comprising the first bearing member.

In utilising the sealing means just described, the pressure on each finger is released thus permitting the lead-- ing edges of a continuous length of textile material and of the transfer material to be passed between the second bearing member and the fingers. Pressure is then applied to each finger so that it is brought into firm contact with the materials, or, if the materials are narrower than the second bearing member, then one or more of the fingers at each end of the second bearing member will then be brought directly into contact with the second bearing member. The leading edges of the materials are then drawn through the remainder of the apparatus into which the sealing means has been incorporated and connected to rewind stands. The pressure on one side of the sealing means is reduced,.for example by use-of a vacuum pump, and the materials are then continuouslydrawn through the sealing means. Howeven due to thefirm pressure of the fingers, little ai riis' drawn through the sealing means.

Byway'jo f illustration, an ,apparatus which is aprefer'r ed embodiment of the] invention will no w be described with referenceto FIGS. I and II of the accompanying drawing swhi ch respectively represent a cross section .of the sealing means, and a front view of the seal.

In FIGS. I and II,"1 represents the top edge of the gap in an apparatus, 2 the bottom edge, and 3 and 4 the side edges of the gap. The bottom edge 2 is preferably curved as shown so that it conforms with the radius of the cylindrical roller 5 mounted on a horizontal axle 6. Atttached to the bottom edge 2 is a flexible sealing strip 7 which runs the full length of the gap and which is pressure or spring loaded so that it is maintained in firm contact with the surface of the cylindrical roller 5. Each finger 8 is mounted on a common axle 9 which is parallel to the axle 6, the bottom edge of each finger being able to bear directly on the lateral face of the cylindrical roller 5. Set into the bottom and front edge of each finger is a flexible sealing strip 10 which runs the full length of the gap and which is attached to the top edge of the gap'1.'(For the sake of clarity the sealing strips 7 and 10 are not shown on FIG. II). Set into the top edge 1 are a series of cylinders 11 each of which bears'against a finger 8, 'said cylinders being provided with pressure means for exerting an independent downwards force on each of the fingers. 4

In operating the apparatus just described pressure is released oneach of the fingers 8, and the free ends of lengths of a textile material 12 and a transfer paper 13 are then passed between the cylindrical roller 5 and the fingers 8, and the free ends are then drawn through the remainder of the apparatus and attached to suitable rewind stands. Pressure is thenappliedthrough the cylinders l1.to' each of the'fingers 8 so that these are brought into firm contact with either the transfer paper 13 or directly, with ,the cylindrical roller-5 when the transfer paper 13 and-the textile material 12 are narrower than the roller 5. A differential pressure is then applied to the two sides of the sealing means, and the transfer material and textile material are then continuously drawn through the seal.

Preferably two such sealing means are used in each apparatus, one of the-sealing means being used as an entrance to the apparatus and the other as an exit, and the interior'ofthe-apparatus being maintained at a pressure'less than atmospheric pressure whilst the exterior of the apparatus is maintained at atmospheric'pressure.

Byway of illustration, an apparatus which is a modification of the embodiment of the invention previously described will now be described with reference to FIG. III ofthe accompanying drawings which represents a cross section of the sealing means.

Comparing FIG. III with FIG. I, the only difference resides in the method of providing the sealing between the fingers 8'and the top edge 1 of the gap. Instead of the'flexible sealing strip 10, a flexible sealing strip 16. which'runs the full length of the gap and is fixed into slots-in the endjwalls 2 and 3 is fixed into a slot 17 in the top edge 1, and is a sliding fit in a slot in the upper portion of each of the fingers 8, so that each of the fingers 8 can freely pivot about the axle 9.

The fingers 8 can if desired be of rectangular crosssection, but in order to minimise ingress of airthrough the sealing means they are preferably constructed so that they are interlocking, and one form of such interlocking is depicted in FIG. [V which represents a'view of suchfingers from'above. In FIG. IV. are shown a series of six fingers 8 pivotable about the axle 9. A portion of each of the two vertical longitudinal faces of each finger is shaped in a saw tooth pattern, 20 and 21., so that consecutive fingers interlock together although they are still able to independently pivot about the axle 9.

Preferably the sealing means is also fitted with a mechanism which facilitates simultaneous raising'of all the fingers 8 so as to permit feeding of the transfer paper and textile material between the cylindrical roller 5 and the fingers.

Whilst the fingers 8 can be constructedof a suitable metal, such as stainless steel, they are preferably obtained by injection moulding of a'suitablelthermoplastic material such as nylon.

The cylindrical roller 5 can be made'of metal, but preferably comprises a cylindrical metal core having an outer layer of a resilient material such'as rubber or polyurethane. The various flexible sealing strips are preferably constructed of a silicone rubber or polyurethane. V

Instead of the first bearing member comprising a large number of individual fingers as shown for example in FIG. II, a number of the fingers in the centre of this bearing member can be combined together, the remaining fingers at each end of the bearing member being separate as previously described.

However, in order that the fingers can adequately minimise ingress of air at the'edges of the web material passing through the sealing means it is necessary that the width of the combined fingers is less than the width of the web material. The loading of the combined fingers is of course independent of the loading on the narrow fingers at each end of the combined fingers.

By way of illustration an apparatus which is a further embodiment of the invention willnow be. described with reference to FIG'. V of the accompanying drawings which represents a cross section of the sealing means.

Comparing FIG. V with FIG. I the only difference resides in the method of providing the bottom bearing member. Instead of the cylindrical roller 5 and the sealing strip 7, the bottom edge 22of the gap terminates in a dome shaped structure 23 the shape of which corresponds to the curved depression 26 in the finger 8, the dome shaped structure 23 running the full length of the gap. Surmounting the top :of the dome shaped structure 23 is a cushion 24 of a compressible material such as rubber or a urethane. In this particular embodiment each of the fingers 8 press the materials 12 and 13 against the cushion 24 on the dome shaped structure, or at the ends of the sealing means (i.e., outside the width of the materials 12 and 13) the fingers 8 bear directly onto the said cushion.

Although the materials 12 and 13 can usually be transported between the adjacent surfaces of the two bearing members without difficulty, it does occasionally happen that the said materials can be adversely affected due to the friction imposed upon them by passage between the two bearing surfaces under pressure.

This can result in damage to the surface of the material or creasing. These disadvantages can be overcome by transporting the materials which are passing through the two bearing members between two continuous flexible belts which also pass between the two bearing members and which are moving at the same speed as the materials themselves. Such an embodiment will now be described with reference to FIG. Vl which represents a cross section of a sealing means fitted with such flexible bands.

The upper part of the sealing means is as described in FIG. I, and the lower part as in FIG. V. Passing between the fingers 8 and the dome shaped structure 23 and running the full width of the gap are two continuous flexible belts 30 and 32 which are mounted on guide rollers, such as 31 and 33, and which are connected to a source of power (not shown) so that they move in the directions indicated by the arrows. The

materials 12 and 13 are sandwiched between the belts and 32, and as the belts are moving at the same speed as the said materials and the bearing surfaces of the two bearing members are not directly pressing on the materials, little or no damage is caused to the materials as they pass through the sealing means.

Such an arrangement involving the use of the flexible belts is in fact used in conjunction with two such sealing means (i.e., into and out of an apparatus, the pressure inside of which is greater or less than atmospheric), the two belts passing through the inlet sealing means and then leaving via the exit sealing means. The materials 12 and 13 are thus transported through the apparatus between the said two belts. The two beltsform continuous separate loops inside and outside of such an apparatus.

It will be understood that details of the apparatus which has been described may be varied without departing from the essential characteristics of the invention, nor have details been given of the necessary ancilliary equipment such as the pressure means for exerting anindependent downwards force on each of the fingers.

Although the said sealing means has been particularly described with reference to its use in an apparatus for carrying out the vacuum transfer colour printing of textile materials, the sealing means can also be used in any other apparatus in which it is desired to transfer a textile material or in fact any material in the form of webs or films across a pressure differential boundary without a substantial flow of air or other gas through the sealing means.

I claim:

l. A sealing means for permitting continuous pasage ofa web material through a gap in a wall separating two zones at different pressures whilst minimising the flow of air'from one zone to the other, comprising, built into the gap, two bearing members between which the web material passes, the first bearing member comprising a series of parallel, closely abutting, fingers which extend the full length of the gap, said fingers being pivoted on an axle which is parallel to a longitudinal edge of the gap, and each of the fingers being pressure loaded towards the second bearing member so as to maintain firm contact with either the web material or with the second bearing member, seals being provided between the fingers and the adjacent edges of the gap and also between the second bearing member and the adjacent edges of the gap,

2. A sealing means as claimed in claim 1 wherein the second bearing member is a cylindrical roller rotatable about a longitudinal axle which is parallel to the lowest edge of the gap.

3. A sealing means as claimed in claim 1 wherein the fingers in the centre of the first bearing member are combined together, the width of the combined unit being less than the width of the web material which is to be passed through the sealing means.

4. A sealing means as claimed in claim 1 which additionally contains two continuous flexible belts which pass between the two bearing members. 

1. A sealing means for permitting continuous pasage of a web material through a gap in a wall separating two zones at different pressures whilst minimising the flow of air from one zone to the other, comprising, built into the gap, two bearing members between which the web material passes, the first bearing member comprising a series of parallel, closely abutting, fingers which extend the full length of the gap, said fingers being pivoted on an axle which is parallel to a longitudinal edge of the gap, and each of the fingers being pressure loaded towards the second bearing member so as to maintain firm contact with either the web material or with the second bearing member, seals being provided between the fingers and the adjacent edges of the gap and also between the second bearing member and the adjacent edges of the gap.
 2. A sealing means as claimed in claim 1 wherein the second bearing member is a cylindrical roller rotatable about a longitudinal axle which is parallel to the lowest edge of the gap.
 3. A sealing means as claimed in claim 1 wherein the fingers in the centre of the first bearing member are combined together, the width of the combined unit being less than the width of the web material which is to be passed through the sealing means.
 4. A sealing means as claimed in claim 1 which additionally contains two continuous flexible belts which pass between the two bearing members. 